How long will instant yeast stay fresh?
Several months, at least, if it's well refrigerated and stored in a covered jar. I buy it in bulk, and until a few years ago (when The Food Mill in Oakland stopped selling it in that form), I actually bought bricks of the stuff . . . They were very heavy, compressed and vacuum sealed. One block would fill nearly a quart jar. Even at the fast clip at which I use yeast, it would take three or four months to go through it, especially with the boys away. Proof it if you have any doubt!! ;o)
I buy the vacuum-packed one-pound bricks. They cost about $5, about 30 times less than buying the equivalent in packets. After opening, I put the package in a zipper bag and store it in the door of the freezer. We make pizza once a week and raisin bread once a month, and the package lasts about six months.
Thanks very much, both of you!